NEWTOWN SQUARE, Pennsylvania - Tiger Woods has been interviewed by US authorities investigating Canadian doctor Anthony Galea, who is charged for unlawfully treating athletes with human growth hormone, the golfer said on Thursday.

The world No 1, who is not accused of any wrongdoing but was a patient of the doctor, said the interview took place in Orlando, Florida, last week.

"I co-operated and answered all their questions and that was it," Woods said after the first round at the AT&T National at Aronimink Golf Club on Thursday.